Click on the "+" icon at the top right of the c9.io page to create a new workspace.

Give your workspace a name and an optional description.

Choose Node.js in the selection area below the name field.

Click the "Create workspace" button.

Once C9 builds and loads your workspace, you should see a terminal window in the lower right hand corner. In this window use the following commands. You don't need to know what these mean at this point.